The goal of the proposed research is to develop experimental, technical, and computational procedures to combine anatomical MRI, MEG, and functional MRI into a composite structural "functional imaging modality that exploits the strengths and minimizes the weaknesses of each component technique. The Specific Aims are: (1) To implement and optimize echo planar fMRI acquisition and analysis techniques tailored for combined fMRI and MEG studies of the human visual system. These include improved systems for visual stimulus presentation and experimental control, and optimized fMRI data acquisition and signal processing strategies suitable for comparative and combined fMRI and MEG studies. (2) To conduct a series of parametric visual activation studies (varying stimulus rate, size, contrast, and location) to serve as a basis for comparison, cross-validation, and integrated analysis of fMRI and MEG using the same sets of stimuli. The rate, size, and contrast experiments will allow selection of optimal trade-offs of stimulus parameters for combined fMRI and MEG. The location (retinotopy) experiment will allow direct comparison of estimates of location and extent of activation provided by the two techniques, and will provide an experimental database for evaluation of alternative strategies for integrated analysis of fMRI and MEG data (3) To compare and evaluate alternative strategies for independent and integrated analysis of fMRI and MEG data, including the incorporation of location and/or orientation constraints on MEG distributed inverse solutions derived from anatomy alone and from anatomy plus fMRI activation. (4) To develop and distribute a software system incorporating the essential capabilities necessary for the comparison and integrated analysis of anatomical MRI, MEG, and fMRI data. This software system will initially be distributed to and evaluated by our collaborators on this proposal and subsequently to a larger group of beta test sites. This system will provide a capability for the combined and integrated analysis of functional imaging data from hemodynamic/metabolic and electromagnetic modalities (e.g., PET, fMRI and MEG, EEG, respectively) that is available from no other source at this time. This project focuses on the integration of MRI, MEG and fMRI because the data types and formats associated with these techniques cover the range encountered in human brain imaging and pose many of the key computational challenges associated with large volumetric and multidimensional data sets. This project will contribute significantly to the long-term goal of building a statistical, volumetric atlas of brain anatomy and functional organization in which information from multiple imaging modalities can be integrated into a unified computational framework for visualization, modeling and information access.